The present invention relates to a method and an apparatus for treating one or more constituents of the blood of a living patient, and more particularly relate to such a method and apparatus which are effective for minimizing the amount of blood removed from the patient for any great period of time as well as for minimizing the amount of physiological saline solution or the like which enters into the body of the patient.
In the present specification, the term "blood constituent" is used not only to refer to typical blood constituents such as red blood corpuscles, white blood corpuscles, blood platelets, and the like, and to liquid blood constituents such as blood plasma and the like, but also to refer to whole blood and to any portion thereof; and the term "treatment of a blood constituent" and similar terms not only are used to refer to administration of treatment to one or more such blood constituents in order for example to remove noxious or useless substances therefrom, to add medicine thereto, to replenish insufficient quantity thereof, or the like, but also are used to refer to application of such treatments as the supplying of a blood constituent or constituents, the replacing of a blood constituent or constituents with one or more other constituents, or the like.
Various illnesses can be cured or mitigated, or their symptoms may be relieved, by administering treatment of a constituent of the blood of the patient. According to the Japanese health insurance practice, six illnesses are regarded as being worthy of such blood constituent treatment from the point of view of payment of medical insurance costs, namely: drug intoxication, acute hepatitis, hyperglobulinemia, hyperlipemia, multiple myeloma, and myasthenia gravis. In addition to these illnesses detailed above, practical and valid instances of the application of such treatment to a large number of conditions such as rheumatoid arthritis, liver failure, erythematosus, and nephritis have been reported. The present invention is intended to promote the effectiveness of treatment for a variety of illnesses, including but not limited to those listed above.
In the prior art, there are various per se known methods and apparatuses, employing adsorbent material or the like, which are currently used with the object of eliminating noxious components in the blood and so on. FIG. 5A of the accompanying drawings shows an exemplary one such apparatus in a schematic view. The principal portion of this apparatus comprises a blood collection portion 32 which is connected to the body of the patient so as to take out a flow of blood therefrom, a blood constituent treatment device 31 which performs some such processing on said flow of blood, and a blood return portion 33 which is connected to the body of the patient so as to return said flow of blood thereto. According to the particular requirements of each individual case, such an apparatus may further comprise various other components not particularly shown, such as a blood pump for maintaining proper blood volume, a blood pressure meter, a blood anticoagulant agent injecting device, a dripper chamber for eliminating air bubbles in the blood, a heater for maintaining an appropriate temperature for the blood while it is outside the body, and so on. Further, if a blood plasma separating device is provided with this apparatus, it is possible to supply the blood constituent treatment device 31 with blood plasma in separated form.
Now, for operating this apparatus, first a quantity of physiological saline solution or the like is pre-filled into the blood constituent treatment device 31, and then, according to the inflow of blood constituents which are to be treated, this physiological saline solution is pushed, by the patient's blood which is flowing out from his or her body via the blood collection portion 32 connected thereto, out of said blood constituent treatment device 31 in the downwards direction in the figure, so as to pass through the blood return portion 33 into the body of the patient while being replaced by said blood from above. And thereafter, after the blood constituent treatment device 31 has become filled up with blood, the blood of the patient continues to circulate through it and is appropriately treated by it, for example by being purified of noxious components contained therein.
Further, as a refinement of such a prior art apparatus, in order to increase treatment capacity, there is a per se known type of prior art blood constituent treatment apparatus as shown in FIG. 5B of the accompanying drawings in a schematic view. In this apparatus, a plurality (two in the illustrated case) of first and second blood constituent treatment devices 31a and 31b are provided in parallel, and are used alternatively. Using conduit switching means including a plurality of switching devices 34, first the blood of the patient containing the constituent to be treated is circulated to the first blood constituent treatment device 31a, by the left pair of said switching devices 34 being opened while the right pair thereof is closed so that the left branch of the apparatus as seen in the figure is utilized. Thus, first the physiological saline solution initially charged into said first blood constituent treatment device 31a is driven out by the inflowing blood and is harmlessly injected into the body of the patient, and thereafter the inflowing blood is appropriately treated in said first blood constituent treatment device 31a. Then, when the processing capacity of said first blood constituent treatment device 31a has become exhausted or deteriorated, said left pair of said switching devices 34 is closed and said right pair thereof is opened. Thus, the apparatus is switched over to the right branch thereof, and first the physiological saline solution initially charged into the second blood constituent treatment device 31b is driven out by the inflowing blood and is harmlessly injected into the body of the patient, and thereafter the inflowing blood is again appropriately treated in said second blood constituent treatment device 31b. Thereby, the fresh processing capability of said second blood constituent treatment device 31b can be utilized.
In order to explain such prior art devices concretely, a practical example of a circuit configuration for treatment of the blood of a patient is shown in FIG. 5C of the accompanying drawings. This exemplary case is a circuit for removing low density and very low density lipoprotein (hereinafter referred to generically as LDL) from blood. Such LDL is considered to be the cause of hyperlipemia, as well as of high blood cholesterol level disease, arteriosclerosis, and the like.
In this exemplary prior art circuit configuration, shown in FIG. 5C there are comprised the following devices: a blood collection portion 1 which is connected to the body of the patient so as to remove a flow of blood therefrom; a blood pump 2 and a collected blood pressure irregularity alarm 3 for maintaining proper blood flow volume; a blood anticoagulant agent injecting device 4 for preventing the coagulation of the blood as it traverses this circuit; a blood plasma separator/combiner device 5 which has the twin functions of (a) separating out blood plasma from the blood passing into it, keeping the blood corpuscles in said blood behind while dispatching said plasma to its plasma side, and (b) remixing together said blood corpuscles and said blood plasma, after said blood plasma has been treated; a blood plasma constituent treatment circuit 9 connected to said blood plasma separator/combiner device 5 on its plasma side; a heater 10 for maintaining the temperature of the blood in the system at an appropriate value; dripper chambers 11 provided at suitable positions in the blood flow path so as to eliminate air bubbles entrained into the blood therein; an air bubble detecting device 12 for detecting any air bubbles which may in any case have passed the dripper chambers 11 and for preventing them passing into the body of the patient; one or more pressure meters 13 located at appropriate circuit points for sensing the pressure of the blood therein; and a blood return portion 14 which is connected to the body of the patient so as to return said flow of blood thereinto. And the blood plasma constituent treatment circuit 9 which is connected to the plasma side of the blood plasma separator/combiner device 5 comprises: a LDL eliminating device 6 which eliminates LDL from the flow of plasma; a plasma pump 7 for regulating and impelling said flow of plasma; a plasma leakage detecting device 8 for preventing blood corpuscles from becoming mixed in with said plasma; further dripper chambers 11; and further pressure meters 13. Blood plasma is separated from the blood taken out from the circulatory system of the patient by the blood plasma separator/combiner device 5, and is outputted from a plasma output port 5a thereof to the blood plasma constituent treatment circuit 9, while the corpuscles in the blood are retained within the body of said blood plasma separator/combiner device 5. After treatment by the LDL eliminating device 6, this blood is recirculated back to the blood plasma separator/combiner device 5 and is inputted through a plasma input port 5b thereof to be remixed with the blood corpuscles remaining therein, so as to form whole blood which then is returned to the circulatory system of the patient.
In FIG. 6 of the accompanying drawings, there is shown a cut-away side longitudinal cross sectional view of the LDL eliminating device 6 incorporated in the FIG. 5C circuit. In this figure, the reference numeral 16 denotes the hollow columnar body of the LDL eliminating device 6, which is filled with a quantity 15 formed in very tiny particles of an appropriate per se known substance which can effectively selectively absorb LDL from blood plasma while being non toxic to the human body. Initially, this body 16 of the device 6 is filled with a quantity of physiological saline solution or the like which holds the quantity 15 of the aforesaid tiny particles in suspension. The upper and lower ends of this hollow columnar body 16 of the LDL eliminating device 16 are closed with covers in which are formed an input port 17a and an output port 17b respectively, and at the top end of the quantity 15 of particulate matter contained in said body 16 there is provided a mesh filter 19 (or the like), on the side of which remote from said quantity 15 of particulate matter there is defined an input plenum 18a, while similarly at the bottom end of said quantity 15 of particulate matter there is provided a membrane filter 20 (or the like), on the side of which remote from said quantity 15 of particulate matter there is defined an output plenum 18b. These filters 19 and 20 prevent the tiny particles of the mass 15 of particulate matter from becoming mixed into the plasma flowing back to the body of the patient via the blood plasma separator/combiner device 5. A typical volume for such an LDL eliminating device 6 is about 400 cm.sup.3, and in the initial state of the system this device 6 contains about 380 cm.sup.3 of the aforesaid dispersion agent of physiological saline solution or the like.
Initially, when the system is first started and blood starts to be taken from the body of the patient, the plasma in this blood, separated out therefrom by the blood plasma separator/combiner device 5, passes through the input port 17a into the input plenum 18a at the top of the LDL eliminating device 6, and pushes downwards and replaces the physiological saline solution contained in the body 15 of said device 6, said physiological saline solution flowing downwards via the output plenum 18b out through the output port 17b to enter the circulatory system of the patient. Thereafter, as the blood plasma comes into contact with the fine particular matter of the particle mass 15, it is purified of LDL, and, as soon as the body 16 of the device 6 is full of plasma and substantially all of the physiological saline solution initially contained therein has been driven out thereof, the purified plasma passes downwards via the output plenum 18b out through the output port 17b to enter the circulatory system of the patient.
As will be clear from the above explanation, when performing blood constituent treatment by the use of such a prior art type of blood constituent treatment apparatus, the interior of the LDL eliminating device 6 becomes filled with blood plasma, and this condition is maintained. Accordingly, only the amount of blood plasma required to fill this device 6 (along with a certain additional amount for filling the intermediate portions of the FIG. 5C circuit) needs to be withdrawn from the body of the patient during the treatment for any considerable time. This may amount to 250 to 400 cm.sup.3 or thereabout. Now, there is a fixed physiological limit (called the maximum permissible external circulation volume) to the amount of blood that can safely be withdrawn for any considerable time period from the circulatory system of a patient, and this limit can be low in the case of a severely ill patient. In any case, it is better to have a lower amount of blood so withdrawn, from the medical point of view. On the other hand, in order to increase the treatment capacity of the blood constituent treatment apparatus, it is very desirable to increase its volumetric capacity, and as a result the desired external circulation volume increases. Accordingly, in the case of using a prior art type of blood constituent treatment apparatus as described above, there is a fixed limit to the treatment capacity.
Further, because the physiological saline solution or the like initially filling the blood constituent treatment apparatus is, in the prior art, passed into the body of the patient, the patient's blood is diluted, and an undesirable reduction in the gelatinous osmotic pressure thereof is caused. As in the case of the problem outlined above with respect to the external circulation volume, as long as the prior art type of blood constituent treatment apparatus as described above is utilized, increase of the volumetric capacity thereof inevitably leads to increase in the volume of physiological saline solution thus diluting the blood of the patient, and there is a medical limit to this dilution also; in any case, such dilution should be kept as low as possible. Thus, from this point of view also, there is a fixed limit to the treatment capacity of such a prior art blood constituent treatment apparatus.
And, further, neither of these problems is alleviated, even if a prior art type of circuit with a plurality of treatment devices arranged in parallel, such as exemplarily shown in FIG. 5B, is utilized.